On paid premium accounts the database server host name is always :

localhost

The MySQL port is 3306 (standard)

To use a MySQL database with your PHP scripts;

1) Make a database in your cpanel/ Mysql section
2) Make a database user in your cpanel/ Mysql section
3) Add your user to your database, and grant all privileges / permissions.
4) In your file manager or ftp locate your script config file.

Then edit / insert that username / password / database name you created into the config file.

Or an easier way to make a DB, User and Password is to click :

DATABASE WIZARD in cPanel this will guide you though making all the necessary user/pass and db name.